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diff --git a/challenge-204/wlmb/perl/ch-1.pl b/challenge-204/wlmb/perl/ch-1.pl
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+#!/usr/bin/env perl
+# Perl weekly challenge 204
+# Task 1:  Monotonic Array
+#
+# See https://wlmb.github.io/2023/02/13/PWC204/#task-1-monotonic-array
+use v5.36;
+die <<~"FIN" unless @ARGV;
+    Usage: $0 N1 [N2...]
+    to test if the sequence N1 N2... is monotonic
+    FIN
+my @orig=@ARGV;
+my $current=shift;
+my ($increasing, $decreasing);
+for(@ARGV){
+    $_>$current and $increasing=1;
+    $_<$current and $decreasing=1;
+    last if $increasing and $decreasing; # shortcut if non monotonic
+    $current=$_;
+}
+my ($result, $reason)=
+    $increasing && $decreasing?(0, "Non-monotonic"):
+    $increasing               ?(1, "Non-decreasing"):
+    $decreasing               ?(1, "Non-increasing"):
+    (1, "Constant");
+say join " ", @orig, "->", $result, $reason;